Chemical decomposition reaction formula for junior high school, chemical decomposition reaction equa

Decomposition reaction: ab=a+b

1. Water decomposes under the action of direct current: 2H2O = energized = 2H2 + O2

Phenomenon: (1) Air bubbles are generated on the electrode. h2:o2 2:1 The gas produced by the positive electrode can rekindle the spark-bearing strips.

The gas produced by the negative electrode can burn in the air, producing a light blue flame.

2. Heating basic copper carbonate: Cu2(OH)2CO3 = = 2CuO + H2O + CO2

Phenomenon: The green powder turns black, water droplets are formed on the inner wall of the test tube, and the clarified lime water becomes turbid.

3. Heat potassium chlorate (with a small amount of manganese dioxide): 2kclo3 = mno2 = 2kcl + 3o2

4. Heating potassium permanganate: 2kmNO4 = = K2mNO4 + MNO2 + O2

5. Hydrogen peroxide is used in the laboratory to produce oxygen: 2H2O2 = MNO2 = 2H2O+ O2

Phenomenon: Bubbles are generated, and the sparkled wooden strips rekindle.

6. Heating mercury oxide: 2hgo = heating = 2hg + o2

7. Calcined limestone: CaCO3 = high temperature = Cao + CO2 (carbon dioxide industrial method).

8. Carbonic acid is unstable and decomposed: H2CO3 === H2O + CO2

Phenomenon: The litmus solution turns from red to purple.

9. Copper sulfate crystals are decomposed by heating: CuSO4 5H2O heats CuSO4 + 5H2O

Suppose that a substance A decomposes under certain conditions and produces three substances.

Then it can be written like this.

a = certain condition = b + c + d

And so on.

Decomposition reaction is one of the four common basic types of chemical reactions, which refers to the reaction of one substance to produce two or more new substances, which can be simply understood as "one becomes many". Some of these reactions are redox reactions and some are non-redox reactions. Decomposition reactions can be classified into different categories according to different classification criteria.

In addition, only the compound can undergo a decomposition reaction. Carbonate, nitrate, and ammonium salts are generally easy to decompose, and the reaction shows a certain regularity.

1. Hydrogen peroxide for oxygen production in the laboratory: 2H2O2 MNO2 2H2O+ O2

2. Heating potassium permanganate: 2kmNO4 heating K2mNO4 + mNO2 + O2

3. Water is divided into 2h2o energized 2h2 + o2 under the action of direct current

4. Carbonic acid is unstable and divided into H2CO3 ==H2O + CO2

5. High-temperature calcined limestone (carbon dioxide industrial method): CaCO3 high-temperature CAO+CO2

6. Hydrochloric acid and caustic soda react: HCl + NaOH ==NaCl + H2O

7. Hydrochloric acid and potassium hydroxide reaction: HCl + KOH ==KCl +H2O

8. Hydrochloric acid and copper hydroxide reaction: 2HCl + Cu(OH)2 ==CuCl2 + 2H2O

9. Hydrochloric acid and calcium hydroxide reaction: 2HCl + Ca(OH)2 ==CaCl2 + 2H2O

10. Hydrochloric acid and iron hydroxide reaction: 3HCl + Fe(OH)3 ==FeCl3 + 3H2O

2h2o2=mno2=2h2o+o2 (up sign).

2kclo3 = mno2 = heating = 2kcl + 3o2 (up sign).

In junior high school, acid-base reactions produce salt and water...Take it as you like.

Decomposition reaction: CaCO3=CaO+CO2 calcined limestone.

Decomposition reaction: 2H2O=2H2+O2 electrolyzed water.

And many more, in the book, summarize it yourself.